In Japan, digital terrestrial television services according to the ISDB-T standard have started since 2003. Moreover, analog broadcasting has been digitalized in each country of the world, such as Europe, North America, South America, and Asia, and digital terrestrial television services have been starting. In many countries, technology, which is equivalent to or based on the ISDB-T standard in Japan, is used. Especially, an OFDM signal, of which orthogonal multiplexing is performed on a plurality of carriers on a frequency axis, is used.
Although the OFDM signal has a characteristic of being resistance to a multipath, in order to further improve quality of reception in reception, performing diversity receiving for every career, which is multiplexed on a frequency axis is proposed (for example, See Document 1).
In order to perform diversity receiving for every carrier, a plurality sets of an antenna and a demodulating unit corresponding thereto (hereinafter called “blanch”) are needed. Each demodulating unit included each branch must be provided with all elements from an element for analog-to-digital converting a received signal to an element for demodulating carriers according to time-frequency conversion independently. For this reason, in prior art, an element for demodulating transmission carriers including control information, such as a modulation method, and an element for detecting frame synchronization.
In the diversity receiving apparatus for every career according to the conventional technology, there is a problem which circuit scale of a receiving apparatus increases. Moreover, in decoding of a transmission control carrier, a memory is needed for the decoding. In detection of frame synchronization, a memory is needed for judgment. Since these memories are needed to be independently provided for every decoding unit, the circuit scale increases.
Moreover, when decoding of the transmission control carrier and/or the frame synchronization are separately provided, in one receiving apparatus, a plurality of results for the decoding of the transmission control carrier and the detection of the frame synchronization can be acquired. However, in the receiving apparatus, since only one result is considered, if there is a plurality of results, the reliability of judgment for the result may become difficult, and the processing procedures until starting the actual decoding after receiving the result may become complicated.
Recently, in order to improve the quality of reception in a mobile terminal, using three or more branches for the diversity receiving has been considered. In this case, increase of the circuit scale and complication of the processing may occur more remarkably.
[Document 1] Published Japanese patent Application 2004-242191